Kerning: ď Dcaron+vowels in bold

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Hello Petr,

The reason for this is that there are two kerning tables, and the older type ('kern') has a limited fixed size (~50,000 pairs). There is not enough room to have every character vs. every character in the first table, so just the basic Latin-based kerns are entered into the first table.

The second table uses a class-based system and can contain the whole-set.

On einteresting research project might be trying to cram the largest possible number of kerns into the first table (depending on available space), based on some statistical analysis of kern-use frequency/visual impact of the full kerning set.

I see, so it's a space problem. By the way, do you place / choose
kerning pairs consistently across variants? I mean, I've noticed
the bold+italics variant seems to have it right.

Or, perhaps, just the right-whitespace-padding (sorry I don't know
the correct term) of d-caron should be adjusted to a similar value
which it has in bold+italics? 'cause there it looks just fine.

One more question: The "second table", how does it work? Does it
mean that only some programs can use hinting from the second
table? Not widely supported yet?

The spacing in bold+italics seems fine.

Petr: the two types of kerning method are:

  'kern' (Kerning Table, TrueType)
  'GPOS (Glyph Positioning, OpenType-only)

In each case there are then a number of sub-variants:

  http://developer.apple.com/fonts/ttrefman/RM06/Chap6kern.html
  http://www.microsoft.com/typography/otspec/gpos.htm#PP

Thanks for clarification and the links, Paul.

Do you think the extra space could be caused by the wrong right
white space setting of d-caron, as I suggest in the comment #3?

If so, the bug could be resolved without need to modify any of the
tables. See the screenshot in comment #4 where it's clear that
bold+italics style has it right (I suppose without kerning).

2010-12-14 (Paul Sladen) Ubuntu Font Family version 0.70

  Release notes 0.70:
  * (Design) Add Capitalised version of glyphs and kern. (Rg, It, Bd,
    BdIt) DM (LP: #676538, #677446)
  * (Design) Give acute and grave a slight upright move to more match
    the Hungarian double acute angle. (Rg, It, Bd, BdIt) (LP: #656647)
  * (Design) Shift Bold Italic accent glyphs to be consistent with the
    Italic. (BdIt only) DM (LP: #677449)
  * (Design) Check spacing and kerning of dcaron, lcaron and
    tcaron. (Rg, It, Bd, BdIt) (LP: #664722)
  * (Design) Add positive kerning to () {} [] to open out the
    combinations so they are less like a closed box. (Rg, It, Bd,
    BdIt) (LP: #671228)
  * (Design) Change design of acute.asc and check highest points (Bd
    and BdIt only) DM
  * (Production) Update <case> feature. DM (LP: #676538, #676539)
  * (Production) Remove Romanian locl feature. (Rg, It, Bd, BdIt)
    (LP: #635615)
  * (Production) Update Copyright information with new
    strings. "Copyright 2010 Canonical Ltd. Licensed under the Ubuntu
    Font Licence 1.0" Trademark string "Ubuntu and Canonical are
    registered trademarks of Canonical Ltd." (Rg, It, Bd, BdIt) DM
    (LP: #677450)
  * (Design) Check aligning of hyphen, math signs em, en, check braces
    and other brackets. 16/11 (LP: #676465)
  * (Production) Pixel per em indicator added at U+F000 (Rg, It, Bd,
    BdIt) (LP: #615787)
  * (Production) Version number indicator added at U+EFFD (Rg, It, Bd,
    BdIt) (LP: #640623)
  * (Production) fstype bit set to 0 - Editable (Rg, It, Bd, BdIt)
    (LP: #648406)

Verified in 0.70.1. Looks much better now. Thanks for the fix!